Flexural behavior of two-layer reinforced concrete slab with hollow cores

Abstract

Flexural behavior of a concrete slab system with an optimal weight-to-strength ratio comprising layered and hollow-core slab structures was investigated using two-layered slabs with hollow cores (LS/HCS). Six slabs with dimensions of 180, 450, and 1600 mm were tested experimentally and numerically using ANSYS software. Each layered slab comprises a 90-mm-thick lightweight concrete bottom layer and a 90-mm-thick high-strength concrete top layer. Three parameters were studied: core diameter (58, 86, and 110 mm), reinforcement ratio (0.37%, 0.53%, 0.95%), and treatment type (bonding agent, nails). Treatment types were analyzed via push-out testing; both nails and agents connected the slabs with sufficient bond strength. A control slab with 86-mm core diameter, shear-span-to-effective-depth ratio of 4, reinforcement ratio of 0.53%, and agent material was used. Concrete, steel bars, and loading support plates were modeled using SOLID65, LINK180, and SOLID185 elements, respectively. Analytical results were validated experimentally. A parametric study analyzed other parameters affecting LS/HCS behavior, including compressive strength, opening numbers, core shape, applied loading type, added top steel reinforcement, slab type, and slab height. Core diameter reduction, increased reinforcement ratios, and using nails enhanced the failure load. The LS/HCS gives an optimum weight-to-strength ratio with a 33.672% reduction compared with solid slabs.